In the metallization of high aspect ratio vias and trenches on semiconductor wafers, it is required that the barrier and seed layer have good sidewall coverage. It is also important to have a void-free metal deposition.
Ionized PVD deposition is used for barrier and seed layer metallization in advanced IC wafers. Ionized PVD provides good sidewall and bottom coverage in via and trench structures. However, as the geometries shrink and as the via dimensions go down below 0.15 micrometers, ionized deposition requirements become more critical. Therefore, it is highly desirable to have an ionized PVD process where bottom and sidewall coverage are well balanced and overhang is minimized.
Accordingly, there is a need to further control the quality of the metal deposited in high aspect ratio vias and trenches during the deposition step.